On the use of tree-ring area as a predictor of biomass accumulation and its climatic determinants of coffee tree growth

The use of growth rings dimensional parameters has been an important tool for the understanding of growth, biomass allocation and climatic characterisation of forest species. However, its potential is unknown in perennial crops of socio-economic importance, such as coffee. This work aimed to understand how the analysis of the growth rings can be used as a proxy to understand the climatic determinants of vegetative growth and biomass allocation in the different organs of coffee trees. The work was carried out in the southern region of Minas Gerais, Brazil. The structure of the growth rings of cross sections of the orthotropic stem of coffee trees (Coffea arabica L. cv. Arara) were analysed from 2011 to 2018, using standard dendrochronological techniques. Each year in that period was characterised climatically and by its bienniality. Pearson correlation statistical analysis was used for mapping the relation among annual radial growth rates of the trees and other assessed parameters as primary growth data, accumulated biomass and the climatic characteristics of the region on an annual and intra-annual scale. During the study the water balance (conditioned by its components, Prec and ETo) and the maximum temperature were the main determinants of the characteristics of the formed ring and the plant biomass allocation. These growing characteristics were also influenced by the phenology that modulates the vegetative/reproductive growth cycles and in turn the biennial production cycles. The results show the potential of tree rings and dendrochronology as a tool that allows indirect, but long-term, assessment of biomass allocation and growth in coffee trees.